Urinary 8-oxo-7, 8-dihydro-2'-deoxyguanosine and biopyrrins levels among construction workers with asbestos exposure history.
(73/1116)
It has been suggested that oxidative stress is associated with the cancers caused by asbestos. Since construction workers are sometimes exposed to low levels of asbestos, we investigated whether oxidative stress was elevated in construction workers who had been exposed to low levels of asbestos. The subjects were 48 Japanese construction workers. The defined asbestos-exposed group consisted of subjects who had the history of suspected exposure to asbestos and were diagnosed to have irregular opacities or pleural plaques. We measured the amount of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) and biopyyrins in the urine of the subjects. The results showed that 8-oxodG and biopyyrins levels in the defined asbestos-exposed group were higher, although they were not statistically significant, than those in the control group. In addition, the urinary 8-oxodG levels tended to correlate positively with the duration of suspected exposure to asbestos. These results suggest that even low-level asbestos exposure may induce oxidative stress and that the resulting's the oxidative stress might be related to lung cancer in construction workers. (+info)
A patient with asbestos-induced lung cancer complicated by silicosis.
(74/1116)
A 76-year-old male died of lung cancer. At first, he was diagnosed as a silicosis, because he had worked for 30 years as a caster in shipyard and large opacities detected by chest x-ray and CT scanning. After the operation of lung cancer, numerous asbestos bodies were observed in the operated lung tissues. The detailed occupational inquiry revealed his asbestos use as a caster in shipyard. Early stage of asbestosis was suspected by chest CT scanning, but not definitely diagnosed in premortal examinations. Asbestosis, pleural plaques, silicosis and large cell carcinoma of the lung were histopathologically confirmed at the autopsy. A patient with asbestos-induced lung cancer complicated by silicosis was rarely published in the literature. (+info)
An operated case of lung cancer with pleural plaques: its asbestos bodies, fiber analysis and asbestos exposure.
(75/1116)
This case was a 79-year-old man with pleural plaques, which had been pointed out in the left lung field on chest X-ray six years ago. A new shadow in the right chest appeared in 1999 and was closely examined. Cytological class IV carcinoma was detected in his lung tissue obtained by broncho-fiberscope. Lobectomy of the right upper lobe was performed, and calcified pleural plaques were found on the chest wall. The clinical diagnosis was poorly differentiated squamous cell carcinoma, T1N0M0. In World War II when he was 26 years old, he had worked as a boiler man on a battle cruiser for one year. The amount of asbestos bodies (AB) was 3,348 per gram dry lung tissue. The cores of AB and asbestos fibers were examined and showed that amosite was the most prevalent and crocidolite, tremolite and chrysotile were present in that order. After leaving the navy, he had worked as a farmer throughout his life, suggesting that he had never contacted asbestos occupationally after being a boiler man. It is strongly suggested that he had been exposed to asbestos during his work as a boiler man and that produced pleural plaques and lung cancer 50 years' later. (+info)
Measurement of airborne fibers: a review.
(76/1116)
Current fiber measurement techniques arose primarily due to health concerns over asbestos exposure. Fiber toxicity appears to be primarily a function of fiber concentration, dimensions and durability in the lungs. There are two basic approaches to fiber measurement. Fibers can be collected on filters and counted or analyzed by light or electron microscopy; alternatively, fibers can be detected directly using a combination of fiber alignment and light scattering techniques. All of these measurement approaches work best when the fibers are simple rod-shaped particles. However, most fibers can exist as curved rods, complex bundles of fibrils, and agglomerates of fibers and compact particles. These non-ideal shapes contribute to measurement bias and variability. (+info)
Asbestos-related lung cancer and mesothelioma in Japan.
(77/1116)
In Japan, crocidolite had been used for asbestos cement pipe and spraying, and amosite had been used for building board and spraying. These two types of asbestos had stopped to use in Japan in the late 1970s. An extreme increase in imported asbestos (all 3 commercial types) was observed between 1960 and 1974. In 1960, 77,000 tons of asbestos were imported, and reached the peak as 352,316 tons in 1974. This extreme rise of asbestos imports corresponds with the recent rapid increase in mortality of malignant pleural mesothelioma. Between 1995 and 1999, an estimated mean annual death from pleural mesothelioma was about 500. The annual number of compensated occupational respiratory cancers due to asbestos exposure has also been increasing. Up to the end of March 2000, 162 cases with malignant mesothelioma and 197 cases with lung cancer were compensated. As for lung cancer, epidemiological studies are scanty in Japan. Limited environmental data of the working places in asbestos textile factories suggests that heavy asbestos exposure in the past made deaths from respiratory diseases. Less asbestos exposure will enable exposed workers to survive enough to reach cancer age. Even now smoking rate among males in Japan are over 50%. So lung cancer deaths caused by the interaction between smoking and asbestos exposure will be continuing. (+info)
Epidemiology of occupational asbestos-related diseases in China.
(78/1116)
In 1950s and 60s, asbestosis had been a major health hazard for asbestos exposed workers. In the late 1970s, lung cancers with or without asbestosis were found among asbestos workers. All cohort studies on asbestos workers and on chrysotile miners in China showed excess deaths from lung cancer. In a large scale of cohort study on asbestos workers, a synergistic effect was found between cigarette smoking and asbestos exposure in the production of lung cancer. There have been not so many cases of malignant mesotheliomas reported, so far. In the cohort of chrysotile miners, 4 cases of pleural mesothelioma were observed. In the large scale of cohort study on asbestos workers in 9 factories using only chrysotile only one case of pleural mesothelioma was detected for 10 years' observation. In another 2 cohort studies, 2 cases of peritoneal mesotheliomas were found, one in Shanghai asbestos factory where a small amount of crocidolite had been used in 1960s, and one in Anqing asbestos factory that was located near tremolite mine. Further study is needed especially for the relationship between exposure to Chinese chrysotile and malignant mesotheliomas. (+info)
Biological effects of asbestos fibers on human cells in vitro--especially on lymphocytes and neutrophils.
(79/1116)
Biological effects of asbestos fibers were reviewed in relation to the polyclonal activation of human lymphocytes and to the release of free radicals from human neutrophils in vitro. Chrysotile, crocidolite, and amosite asbestos activate CD4+ T lymphocytes polyclonally, followed by activation-induced cell death (a type of apoptosis). The activation is HLA class II dependent, and certain Vbeta repertoire, e.g. Vbeta 5.3, are detected among the fractionated T cells with a high Ca++ level that had been stimulated by asbestos fibers. These observations support the possibility that asbestos acts as a superantigen, and that asbestos stimulate lymphocytes repeatedly in vivo. It has been reported that asbestos-induced cytotoxicity can be suppressed by the scavengers of superoxide or hydroxyl radical. Some of these scavengers such as dimethylsulfoxide (DMSO) or retinoic acid are known as inducers of cell differentiation. The biological functions of DMSO for cell differentiation of HL-60 cells to neutrophils are suppressed by co-culturing of crocidolite asbestos, because DMSO reacts with the hydroxyl radical released after the stimulation with crocidolite and spent itself. Superoxide dismutase (SOD) inhibited the effects of crocidolite, reacting rapidly with *O2- before the secondary release of *OH. It seems to be probable that asbestos fibers, especially crocidolite, suppress the tissue cell differentiation by releasing free radicals and by wasting inducers of cell differentiation as radical scavengers. (+info)
In vitro studies on biological effects of fibrous minerals.
(80/1116)
Asbestos substitutes have been used recently in industrial various applications. Since certain asbestos substitutes have similar characteristics of asbestos, they require urgent in vitro and in vivo evaluation of these asbestos substitutes prior to occupational applications. Though in vitro studies do not offer precise assessment of toxicity of the fibers, it is possible to provide useful information as to the biological effects of asbestos and its substitutes. This review articles described the findings of in vitro experiments in investigation of biological effects of asbestos and man made mineral fibers (MMMF) and their correlation with in vivo assays; 1. Cytotoxicity, geometry and dimension of fibers. 2. In vitro biological effects of fibers on a mass basis and a numerical basis. 3. Mechanism of cytotoxicity, carcinogenecity and cell proliferation including in vitro cytokines production. The relationships between the in vitro and the in vivo biological effects of fibers do not always coincide. Therefore, safety of the fibers must be assessed in both in vivo and in vitro using an inert fiber as negative control. Additionally, evaluation of safety of these fibers in vitro must be conducted in comparable concentrations, sizes and numbers of fibers for used in in vivo experiments. (+info)